What is a big enough gap?

Ooooohhhh out riding with Mr and we got into a debate about what is classed as a big enough gap for the purposes of lane changing / weaving.

My idea: 3 ft. His idea: 7ft. Lol, bit of a variation 🤷🏻‍♀️

My measurement is based on all three vehicles being in motion (A = fast lane higher speed, B= slow lane lower speed, green sombrero = me) and allowing for A to move slightly more in front during the manoeuvre and B to drop back further than it was at the start thereby increasing the gap while lane change is in progress.

Also going on the assumption rider checks mirrors and speeds up as necessary, B doesn’t speed up and A doesn’t slow down just to be a dickhead. Anyone who knows me understands my love of filtering and the skill at which I can complete this task. Zero effort on my part it is the only skill I have mastered so far in regards to riding.

As previously mentioned in other posts, Mr does not usually filter due to his shift work so has not had as much experience even though he has been riding much longer.